For example, as an electric rotating machine, there is a synchronous motor generator that is activated as a single motor or generator.
In the hybrid vehicle, an engine and two motor generators are coupled and interlocked to a wheel drive system via a power distribution mechanism, in which one of the motor generators is used for engine start, power assist, and power generation while the other one is used for other purposes such as power assist and regenerative power generation, as disclosed in the Patent Literature 1.
According to Patent Literature 2, two motor generators are connected directly so that both of the motor generators serve as a motor or generator, or one of the motor generators is used as a motor and the other one is used as a generator.
Patent Literature 3 discloses an induction motor and a synchronous motor in which both stators are opposed to each other on inner and outer peripheral surfaces of a cylindrical rotor and both stators have coils with electrical angles shifted from each other by 180 degrees in the circumferential direction.
A rotary electric machine using the principle of inductive repulsion and attraction as disclosed in Patent Literature 4 is configured to generate an electromagnetic force that is to make a permanent magnet rotator return to the center by superimposing, onto a three-phase current that is supplied to a stator of the rotary electric machine using the principle of inductive repulsion and attraction and synchronized to the rotational speed of the permanent magnet rotator, a current shifted from the three-phase current by 90°.
Patent Literature 5 discloses a rotary frequency converter configured such that a motor and a generator are coupled by a shaft so as to deliver and receive power between systems with different frequencies.